Three dimensional bag and method and apparatus for making same



March 6, 1962 T. E. PIAZZE THREE DIMENSIONAL BAG AND METHOD ANDAPPARATUS FOR MAKING SAME 3 Sheets-Sheet 1 Filed Aug. 21, 1957 INVENTORT/zomas EP/ azze BY Wfim, f zz/M44; fig;

March 6, 1962 T. E. PIAZZE THREE DIMENSIONAL BAG AND METHOD ANDAPPARATUS FOR MAKING SAME 3 Sheets-Sheet 2 Filed Aug. 21, 1957 ORNEYSINVENTOR r/zom as E Biazze fnzz, AMW J BY WW,

March 6, 1962 T. E PIAZZE THREE DIMENSIONAL BAG AND METHOD AND APPARATUSFOR MAKING SAME 5 Sheets-Sheet 3 INYENTOR ATTORNEYS United States Patentw 3,023 679 THREE DllVIENSIONAL BAG AND METHOD AND APPARATUS FOR MAKINGSAME Thomas E. Piazza, Mount Vernon, Ohio, assignor to Contlnental CanCompany, Inc, New York, N.Y., a corporation of New York Filed Aug. 21,1957, Ser. No. 679,455 11 Claims. (Cl. 93-8) This invention relates tonovel flexible bags and to a novel apparatus and method for fabricatingsuch bags from thin heat-scalable plastic material, for examplecellophane or Pliofilm.

One object of the invention is to provide a novel unit normally in flatform but readily expansible into the form of a bag having substantiallyrectangular side and edge walls and a substantially rectangular bottom,and having uniquely related seams formed by heat-sealing edges of thethermo-plastic material together.

The flat unit includes two opposed side walls, each of said side wallshaving two side edges disposed in parallel relation from the upper edgeof the wall to points near the lower edge thereof. The lower endportions of these side edges, however, converge downwardly from saidpoints to said lower edge. An upwardly projecting accordion pleat isdisposed between the lower end portions of the two side Walls and hasthe lower edges of its two walls integrally joined to the lower edges ofsaid side walls. The central fold line of the accordion pleat has itsends disposed at the aforesaid points. The end edges of the accordionpleat converge downwardly and are heatsealed to the downwardlyconverging lower ends of the side edges of the two side walls, and thevertical major portions of said side edges are heat-sealed together fromthe aforesaid ends of the central fold line of the pleat to the upperend of the unit.

When the above described flat unit is expanded into bag form, the twoside Walls of said unit form two side walls and two edge walls for thebag, the accordion pleat opens and forms the bag bottom, and the endportions of this pleat form triangular gussets integral with said bottomand heat sealed to said edge walls of the bag.

The invention aims to provide a simple, practicable and rapid method forsuccessfully shaping, cutting and heat-sealing the units in largequantities, with no danger of the sides of the accordion pleats becomingfused together.

A substantially flat tube of the desired flexible plastic is formed andthe longitudinal edge portions of this fiat tube are inwardly deformedto provide each of said edge portions with an inwardly projectinglongitudinally extending accordion pleat. The flat tube is thenlongitudinally cut into two longitudinal halves each having one of theaccordion pleats. These halves are then transversely cut into separatebag forming units and the thus formed edges of each unit are heat-sealedtogether simultaneously with the transverse cutting operations. Duringperformance of these cutting and sealing operations, the walls of theaccordion pleat are prevented from becoming fused together by means ofanti-blocking coating applied to the portions of the plastic which formsaid pleat walls. For these coatings, straight shellac diluted inalcohol and acetone may well be used. After they are applied and thesolvents dissipated, the shellac which is non-compatible to the plastic,prevents welding together of the walls of the accordion pleats.

The invention further aims to provide for forming the above mentionedflat tube either by flattening a cylindrical plastic tube or by foldinga plastic Web, the nonblocking coatings in either case being applied tothe plastic in the form of stripes.

A still further aim of the invention is to provide a ice 2. novelapparatus for use in performing the required method steps.

With the above and other objects in view that will hereinafter appear,the nature of the invention will be more clearly understood by referenceto the following detailed description, the appended claims and theseveral views illustrated in the accompanying drawings.

In the drawings:

FIGURE 1 is a diagrammatic side elevation, partly in section, showingone form of the apparatus.

FIGURES 2, 3 and 4 are detail horizontal sectional views on lines 2-2,3-3 and 4-4 of FIGURE 1.

FIGURE 5 is an enlarged diagrammatic top plan view, partly broken awayand in section, of the apparatus shown in FIGURE 1.

FIGURE 6 is a further enlarged transverse sectional view on line 6-6 ofFIGURE 1.

FIGURE 7 -is a view similar to FIGURE 1 but showing another form ofapparatus.

FIGURE 8 is a fragmentary elevation as indicated by the arrow 8 ofFIGURE 7.

FIGURE 9 is an enlarged transverse sectional view on line 9-9 of FIGURE7.

FIGURE 10 is a perspective view of the lower end portion of one of theflat bag-forming units.

FIGURE 11 is a perspective view of the lower end portion of one of thefully opened bags.

FIGURES l2 and 13 are vertical sectional views'on lines 1212 and 1313 ofFIGURES 10 and 11, respectively.

In the apparatus shown in FIGURES l, 5 and 6, two continuously drivenpull rolls 1 and 2 are provided for pulling a cylindrical plastic tube 3downwardly from an extrusion die and gradually converting saidcylindrical tube into a flat tube 4. Creasing plates or disks 5 areprovided above the pull rolls 1 and 2 for inwardly deforming thelongitudinal edge portions of the Hat tube 4 to provide said edgeportions with inwardly projecting, longitudinally extending accordionpleats 6. Before these pleats 6 are formed, the portions of the tube 3from which they are to be formed, are coated with stripes 7 ofnon-blocking material, by means of spray nozzles 8. This non-blockingmaterial is preferably straight shellac diluted in alcohol and acetone.The solvent, however, is evaporated from the stripes 7 by a suitabledryer 9 and these stripes are then non-compatible to the plastic.Consequently, the walls 10 of the accordion pleats 6 are prevented frombecoming fused together when heat-sealing of cut edges of the plastic islater effected.

A belt support 11 is horizontally spaced from the pull rolls 1 and 2,and the upper reach of a belt 12 passes over said support 11 tohorizontally support the fiat tube 4. A feed roll 13 coacts with'thereceiving end of the belt 12 and both said feed roll and belt areintermittently driven to advance the flat tube 4, step by step.

Between the roll 2 and the roll 13, a slitting knife 14 and coactingroller 15 are provided to longitudinally cut the flat tube 4 into twolongitudinal halves 16, each of which has one of the accordion pleats 6.

Over the'belt 12 a suitably heated cutting means 17 is provided totransversely cut the advanced flat tube halves 16 into separate bagforming units 18 and to heat-seal the thus-formed edges of the plastictogether. The cutting means 17 is vertically reciprocated and descendsafter each advance step imparted to the tube halves 16. During suchcutter operation, a loop 19 (FIGURE 1) forms in the flat tube 4 due tothe constantly driven feed rolls 1 and 2. This loop supplies therequired tube length for the next step imparted to the tube by the feedroll 13 and belt 12.

A take-away roll 20 pulls each unit 18 away from the 3 cutting means 17and a discharge roll 21 delivers the successively completed units to areceiver 22.

The cutting means 17 includes an elongated straight knife 23 which cutsthe tube halves 16 from the inner fold line 24 of one of said halves tothe corresponding fold line of the other of said halves. The cuttingmeans 17 also includes two diverging knives 25 at each end of the knife23, for cutting the pleated edge portions of the two halves 16.

The triangular scraps of plastic cut from the pleated edge portions ofthe flat tube halves 18 are lifted by intermittently actuated suctionarms 26 and delivered to suction conduits 27 which convey them away aswaste.

As shown in FIGURES and 12, each flat unit 18 includes two opposed sidewalls 28. Each of these side walls has two side edges 29 disposed inparallel relation from its upper edge to points 30 near its lower edge31. The lower end portions 32 of the side wall edges 29 convergedownwardly from the points 30 to the lower edge 31. The accordion pleat6 is disposed between the lower end portions of the two side walls 28,and the ends of the inner fold line 24 of said pleat are located at thepoints 30. The lower edges of the pleat walls 10 are integral with thelower edges 31 of the side walls 28, and the end edges 33 convergedownwardly and extend along the above described edges 32. The end edges33 of one of the pleat walls 10 are heat-sealed to the edges 32 of oneof the side walls 28: and the corresponding end edges of the other ofsaid pleat walls 10 are heat-sealed to the edges 32 of the other of saidside walls 28. The side edges 29 of the two side walls 28 are heatsealed together. All of the heat-sealing of the various edges waseffected by the heated cutting means 17 as it formed said edges.

When the unit of FIGURES 10 and 12 is opened to the fully expandedcondition of FIGURES 11 and 13, the bag thus produced has two spacedrectangular side walls 34, two edge walls 35, a rectangular bottom 36and two triangular gussets 37. Each edge wall 35 has two verticallyelongated sections 38 integral with the side walls 34, said sections 38having vertical inner edges 39 which are heat-sealed together from theirupper ends to a point 40 near the lower end of the bag. The two sections38 have lower end edges 41 which diverge downwardly from the point 40 tothe lower edges 42 of the side walls 34. The longitudinal edges of thebottom 36 are integral with the lower edges 42 of the side walls 34: andthe triangular gussets 37 are integral with the ends of said bottom.These gussets extend upwardly from the bottom 36 in the planes of theedge walls 35 and have upwardly converging edges 43 which areheat-sealed to the end edges 41 of the edge wall sections 38.

In FIGURE 7, an apparatus is shown for forming a flat tube 4a from aflat web 3a. The elements 5a, 1a, 2a, 14a, a, 12a, 13a, 11a, 17a and 26aare identical with the corresponding elements of FIGURE 1 and performthe same functions. Various guide rolls 44 are provided for the Web 3aand means 45 is provided for applying stripes 7a of non-blockingmaterial to said web before it is folded to form the tube 4a. Thelongitudinal center of each stripe 7a is spaced inwardly from therelated longitudinal edge of the web 3a a distance equal to about onefourth of the width of said web. Suitable conventional means 46 areemployed to inwardly fold the longitudinal edge portions 47 of the Web3a to form the flat tube 4a. As the upper wall of this tube has theequivalent 48 of a longitudinal slit, the knife 14a cuts only throughthe lower wall of the tube.

Either form of apparatus performs the steps of forming a flat flexiblethermo-plastic tube and inwardly deforming the longitudinal edgeportions thereof to provide each of said edge portions with an inwardlyprojecting longitudinally extending accordion pleat, longitudinallycutting said flat tube into two longitudinal halves each having one ofsaid accordion pleats, transversely cutting said halves into separatebag-forming units and heat-sealing together the thus-formed edges ofeach separate unit, and preventing heat-sealing of the side walls ofsaid accordion pleats together during performance of the transversecutting operations. Also, with either form of apparatus, each transversecutting operation is performed on a straight line from one of theaccordion pleats to the other and is performed on an oblique line acrosseach of said pleats, each oblique cut being at an obtuse angle to thecontiguous straight cut.

It will be seen from the foregoing that a novel and advantageous method,a novel and advantageous apparatus, a novel and advantageous flat unitexpansible into bag form, and a novel and advantageous three-dimensionalbag, have been disclosed. However, attention is invited to thepossibility of making variations, within the scope of the invention.

I claim:

1. In a method of manufacturing plastic bags, the steps of forming aflat flexible thermo-plastic tube and inwardly deforming thelongitudinal edge portions thereof to provide each of said edge portionswith an inwardly projecting longitudinally extending accordion pleat,longitudinally cutting said flat tube in two longitudinal halves eachhaving one of said accordion pleats, transversely cutting said halvesinto separate bag-forming units and heat-sealing together thethus-formed edges of each separate unit, and preventing heat-sealing ofthe side walls of said accordion pleats together during performance ofthe heatsealing operations by the application of coatings which are notheat-scalable to the areas of the plastic which form the contiguousfaces of said pleat side walls.

2. The method defined in claim 1 in which the operation of forming saidfiat tube comprises flattening a preformed cylindrical tube.

3. The method defined in claim 1, in which the operation of forming saidflat tube comprises inward folding of longitudinal edge portions of afiat web onto the interventing portion of said web.

4. An apparatus for forming plastic bags from a substantial-lycylindrical thermoplastic tube, comprising means for externally applyingtwo longitudinal stripes of non-blocking material to diametricallyopposite portions of the cylindrical tube, means for deforming thestriped cylindrical tube into the form of a flat tube having twoinwardly projecting longitudinally extending accordion pleats at itsedges, said pleats being formed by the striped portions of the tube,means for longitudinally cutting the fiat pleated tube into twolongitudinal halves each having one of said pleates, and heated cuttingmeans for transversely outing said halves into bag-forming units andsimultaneously heat-sealing the cut edges of said units together.

5. A structure as specified in claim 4, in which said heated cuttingmeans comprises a straight knife for outting through the flat tubehalves from one of said pleats to the other, and diverging knives at theends of said straight knife for cutting through the pleated edgeportions of said tube halves.

6. An apparatus for forming plastic bags from a thermoplastic web,comprising means for applying two longitudinal stripes of non-blockingmaterial to one side of the web, the center line of each stripe beingspaced from one edge of the Web a distance which is about one fourth ofthe web width, means for inwardly folding the longitudinal edge portionsof the web to form a flat tube and for inwardly deforming thelongitudinal edge portions of said tube to provide two inwardlyprojecting longitudinally extending accordion pleats, said pleats havingsaid stripes on the inner faces of their opposed sides, means forlongitudinally cutting the flat pleated tube into two longitudinalhalves each having one of said pleats, and heated cutting means fortransversely cutting said halves into bag-forming units andsimultaneously heatsealing the cut edges of said units together.

7. A structure as specified in claim 6, in which said heated cuttingmeans comprises a straight knife for cutting throught the fiat tubehalves from one of said pleats to the other, and diverging knives at theends of said straight knife for cutting through the pleated edgeportions of said tube halves.

8. In a method of manufacturing plastic bags, the steps of forming aflat thermo-plastic tube and inwardly deforming longitudinal edgeportions thereof to provide each of said edge portions with an inwardlyprojecting longitudinally extending accordion pleat, longitudinallycutting said pleated fiat tube into longitudinal halves each having oneof said accordion pleats, and in a single operation transversely cuttingsaid pleated tube halves into separate bag-forming units andheat-sealing together edges of each separate bag-forming unit whilepreventing heatsealing of side walls of said accordion pleats togetherduring the performance of the heat-sealing operations, said side Wallsof said accordion pleats being prevented from becoming heat-sealedtogether by the application of coatings which are not heat-scalable tothe areas of the plastic which form the contiguous faces of said pleatside walls.

9. In a method of manufacturing plastic bags, the steps of forming aflat thermo-plastic tube and inwardly deforming longitudinal edgeportions thereof to provide each of said edge portions with an inwardlyprojecting longitudinally extending accordion pleat, applying andadhering to the areas of the tube which form the contiguous faces of thepleat side walls a means for preventing the heat-sealing together of theopposing faces of the pleat side walls, longitudinally cutting saidpleated fiat tube into longitudinal halves each having one of saidaccordion pleats, and in a single operation transversely cutting saidpleated tube halves into separate bag-forming units and heat-sealingtogether edges of each separate bag-forming unit while the meansprevents heat-sealing of side walls of said accordion pleats togetherduring the performance of the heat-sealing operations.

10. The method of claim 9 wherein the heat-sealing preventing means isapplied to the tube prior to the formation of the accordion pleats.

11. The method of claim 9 wherein the heat-sealing preventing means isapplied to the tube prior to the formation of the accordion pleats andis permanently adhered to the tube.

References Cited in the file of this patent UNITED STATES PATENTS2,185,647 Penn et al. Jan. 2, 1940 2,615,375 Rowe et al. Oct. 28, 19522,631,332 Reber Mar. 17, 1953 2,690,199 Bennorth Sept. 28, 19542,707,985 Binnall May 10, 1955 2,788,039 Schjeldahl Apr. 9, 19572,800,163 Rusch July 23, 1957 2,815,063 La Fleur Dec. 3, 1957 FOREIGNPATENTS 1,044,871 France June 24, 1953

